The invention relates to a lighting or signaling device for a vehicle.
Such a device is known from the document EP-0 847 894, comprising a casing carrying a lamp, glazing and an intermediate piece linking the glazing to the casing. The casing and the intermediate piece are generally made of plastic. However, it is observed that the heat given off by the lamp heats up the air inside the device, and that this hot air rises so as to heat up the upper part of the intermediate piece. This rise in temperature, though, could, in certain applications, for example in the case of a fog lamp, cause deformation of the intermediate piece and dislocating of the glazing. It is known that, especially in a fog lamp, the temperature of certain regions may reach 200xc2x0 C.
An object of the invention is to provide a lighting or signaling device in which the intermediate piece is at less risk of being deformed.
With a view to achieving this object, a lighting or signaling device for a vehicle is proposed, according to the invention, including a casing, glazing and an intermediate piece linking the glazing to the casing, further including a screen extending forwards from an upper region of the casing towards the glazing, the screen being linked directly to the casing so forming a single piece with the casing.
Thus, the screen receives the rising hot air. A fraction of the heat is therefore picked up by the screen and no longer by the intermediate piece. Hence the risk of the latter being deformed is reduced. As for the screen, it can be deformed to a large extent without impairing the functioning of the device.
The device according to the invention could, moreover, feature at least any one of the following characteristics:
the screen is molded integrally with the casing;
the screen and the casing each feature an inner face and an outer face, at least one of the inner or outer faces of the screen being in the extension of the corresponding face of the casing;
the screen has a generally cylindrical shape;
the screen extends over an angular sector less than 90xc2x0 around an axis of the device.
Advantageously, the device comprises a back wall made of plastic, a lamp holder fixed to the back wall and a metal plate fixed to the back wall.
Thus, the metal plate reinforces and stiffens the back wall. The mechanical resistance of the wall, even under the effect of the heat, is thus increased. Moreover, the metal plate receives some of the heat from the back wall, or, what is more, even receives the heat from the lamp directly, and dissipates it into the air surrounding the plate (by forming a radiator) which keeps the back wall at a relatively low temperature. Thus reinforced, and heated less, the back wall is less deformed. Hence the positioning of the lamp with respect to the reflector is preserved, so that the correct beam is obtained.
Advantageously, the device includes a reflector and a cradle linking the reflector to the casing and featuring an aperture in its upper part.
Thus, the aperture corresponds to the region of the cradle which otherwise would be most exposed to the heat. Moreover, the aperture allows a certain amount of dilation of the cradle. The thermal behavior of the cradle is thus enhanced, which promotes correct positioning of the reflector with respect to the lamp. Moreover, this aperture reduces the volume of the cradle and gives it an overall size allowing certain kinematics for fitting the cradle with respect to the reflector, such as assembly by pivoting, for example, which otherwise would be prohibited. Moreover, this aperture achieves an indexing effect for the correct fitting of the cradle into the device. Finally, it gives rise to a reduction in material. This results in a saving in weight and in cost, which is all the more important since high-grade plastics, which have good heat resistance but are often expensive, are usually used for this type of piece.
Advantageously, what is involved is a headlight.
Advantageously, what is involved is a fog lamp.
Other characteristics and advantages of the invention will emerge further from the following description of a preferred embodiment and of variants which are given by way of non-limiting examples.